Merge pull request #1664 from bbrk24/range-efficiency

Range literal improvements: faster, fix doubly strict

source/parser/for.civet

@@ -46,9 +46,6 @@ function processRangeExpression(start: ASTNode, ws1: ASTNode, range: RangeDots,
         Math.abs
   lengthAdjust :=
     1 - Number(not range.left.inclusive) - Number(not range.right.inclusive)
-  lengthAdjustExpression :=
-    if lengthAdjust > 0 then ` + ${lengthAdjust}`
-    else if lengthAdjust < 0 then ` - ${-lengthAdjust}`
 
   let children: Children?
   if start is like {type: "Literal"} and end is like {type: "Literal"}
@@ -75,9 +72,12 @@ function processRangeExpression(start: ASTNode, ws1: ASTNode, range: RangeDots,
           . "]"
       else
         children =
-          . `Array.from({length: ${length.toString()}}, `
-          . "(_, i) => String.fromCharCode(", startCode.toString()
-          . step > 0 ? " + " : " - ", "i))"
+          . getHelperRef startCode <= endCode ? "stringRange" : "revStringRange"
+          . "("
+          . startCode.toString()
+          . ", "
+          . length.toString()
+          . ")"
       children.unshift range.error if range.error?
     else if startValue <? "number" and endValue <? "number"
       step := startValue <= endValue ? 1 : -1
@@ -97,21 +97,27 @@ function processRangeExpression(start: ASTNode, ws1: ASTNode, range: RangeDots,
       sign := range.increasing ? "+" : "-"
       end = makeLeftHandSideExpression end
       children =
-        . "((s) => Array.from({length: "
-        . range.increasing ? [ws2, end, " - s"] : ["s - ", ws2, end]
-        . lengthAdjustExpression
-        . "}, (_, i) => s ", sign, " i))"
+        . getHelperRef range.increasing ? 'range' : 'revRange'
         . "("
         . if range.left.inclusive
             start
           else
             [makeLeftHandSideExpression(start), ` ${sign} 1`]
+        . ","
+        . if range.right.inclusive
+            [makeLeftHandSideExpression(end), ` ${sign} 1`]
+          else
+            end
         . ...ws1, ")"
     else
       children =
-        . "((s, e) => {let step = e > s ? 1 : -1; return Array.from({length: Math.abs(e - s)"
-        . lengthAdjustExpression
-        . "}, (_, i) => s + i * step)})"
+        . "((s, e) => s > e ? "
+        . getHelperRef("revRange"), "(s, e"
+        . if range.right.inclusive then " - 1"
+        . ") : "
+        . getHelperRef("range"), "(s, e"
+        . if range.right.inclusive then " + 1"
+        . "))"
         . "(", start, ...ws1, comma, ws2, end, ")"
 
   {

source/parser/helper.civet

@@ -63,15 +63,16 @@ declareHelper := {
       }
       "\n"
     ]]
-  rslice(rsliceRef): void
-    RSliceable := makeRef "RSliceable"
+  RSliceable(RSliceableRef): void
     state.prelude.push ["",
-      ts [ "type ", RSliceable, "<R> = string | {length: number; slice(start: number, end: number): {reverse(): R}}\n" ]
+      ts [ "type ", RSliceableRef, "<R> = string | {length: number; slice(start: number, end: number): {reverse(): R}}\n" ]
     ]
+  rslice(rsliceRef): void
+    RSliceableRef := getHelperRef "RSliceable"
     state.prelude.push ["", [
       preludeVar
       rsliceRef
-      ts [ ": <R, T extends string | ", RSliceable, "<R>>(a: T, start?: number, end?: number) => T extends string ? string : T extends ", RSliceable, "<infer R> ? R : never" ]
+      ts [ ": <R, T extends string | ", RSliceableRef, "<R>>(a: T, start?: number, end?: number) => T extends string ? string : T extends ", RSliceableRef, "<infer R> ? R : never" ]
       " = ((a, start = -1, end = -1) => {\n"
       "  const l = a.length\n"
       "  if (start < 0) start += l\n"
@@ -87,6 +88,76 @@ declareHelper := {
       "  }\n"
       "})"
     ], ";\n"]
+  range(rangeRef): void
+    state.prelude.push ["", [
+      preludeVar
+      rangeRef
+      ts [ ": (start: number, end: number) => number[]" ]
+      " "
+      """
+      = (start, end) => {
+        const length = end - start;
+        if (length <= 0) return [];
+        const arr = Array(length);
+        for (let i = 0; i < length; ++i) {
+          arr[i] = i + start;
+        }
+        return arr;
+      }
+      """
+    ], ";\n"]
+  revRange(revRangeRef): void
+    state.prelude.push ["", [
+      preludeVar
+      revRangeRef
+      ts [ ": (start: number, end: number) => number[]" ]
+      " "
+      """
+      = (start, end) => {
+        const length = start - end;
+        if (length <= 0) return [];
+        const arr = Array(length);
+        for (let i = 0; i < length; ++i) {
+          arr[i] = start - i;
+        }
+        return arr;
+      }
+      """
+    ], ";\n"]
+  stringRange(stringRangeRef): void
+    state.prelude.push ["", [
+      preludeVar
+      stringRangeRef
+      ts [ ": (start: number, length: number) => string[]" ]
+      " "
+      """
+      = (start, length) => {
+        if (length <= 0) return [];
+        const arr = Array(length);
+        for (let i = 0; i < length; ++i) {
+          arr[i] = String.fromCharCode(start + i);
+        }
+        return arr;
+      }
+      """
+    ], ";\n"]
+  revStringRange(revStringRangeRef): void
+    state.prelude.push ["", [
+      preludeVar
+      revStringRangeRef
+      ts [ ": (start: number, length: number) => string[]" ]
+      " "
+      """
+      = (start, length) => {
+        if (length <= 0) return [];
+        const arr = Array(length);
+        for (let i = 0; i < length; ++i) {
+          arr[i] = String.fromCharCode(start - i);
+        }
+        return arr;
+      }
+      """
+    ], ";\n"]
   div(divRef): void
     state.prelude.push ["", [ // [indent, statement]
       preludeVar
@@ -194,10 +265,21 @@ function peekHelperRef(base: HelperName): ASTRef?
  * Extract a subarray of the prelude array that just contains the
  * helper functions used in the given subtree
  */
-function extractPreludeFor(node: ASTNode): ASTNode[]
-  helpers .= new Set Object.values state.helperRefs
-  helpers = new Set gatherRecursive node, helpers@has
-  state.prelude.filter (s) => (gatherRecursive s, helpers@has)#
+function extractPreludeFor(node: ASTNode): StatementTuple[]
+  return state.prelude unless state.prelude#
+  allHelpers := new Set Object.values state.helperRefs
+  isHelper := allHelpers@has as (node: ASTNode) => node is ASTRef
+  usedHelpers := new Set gatherRecursive node, isHelper
+  // Find helpers used within helpers
+  loop
+    prelude .= state.prelude.filter (s) =>
+      (gatherRecursive s, usedHelpers@has as (node: ASTNode) => node is ASTRef)#
+    changed .= false
+    for each helper of gatherRecursive prelude, isHelper
+      unless usedHelpers.has helper
+        usedHelpers.add helper
+        changed = true
+    return prelude unless changed
 
 export {
   extractPreludeFor

source/parser/lib.civet

@@ -151,7 +151,11 @@ import {
 } from ./unary.civet
 import { createConstLetDecs, createVarDecs } from ./auto-dec.civet
 import { expressionizeComptime, processComptime } from ./comptime.civet
-import { getHelperRef, peekHelperRef } from ./helper.civet
+import {
+  extractPreludeFor
+  getHelperRef
+  peekHelperRef
+} from ./helper.civet
 
 import {
   dedentBlockString
@@ -1590,8 +1594,8 @@ function processProgram(root: BlockStatement): void
 
   processCoffeeClasses(statements) if config.coffeeClasses
 
-  // Insert prelude
-  statements.unshift(...state.prelude)
+  // Insert prelude, dropping any actually unused helpers
+  statements.unshift ...extractPreludeFor statements
 
   if config.autoLet
     createConstLetDecs(statements, [], "let")

test/compat/coffee-range.civet

@@ -1,6 +1,47 @@
-{ testCase } from "../helper.civet"
+{ testCase, evalsTo } from "../helper.civet"
 
 describe "coffeeRange", ->
+  it "coffeeRange behaves like range", ->
+    evalsTo """
+      "civet coffeeRange"
+      [0..100]
+    """, [0..100]
+
+    evalsTo """
+      "civet coffeeRange"
+      [0...100]
+    """, [0...100]
+
+    evalsTo """
+      "civet coffeeRange"
+      [100..0]
+    """, [100>=..>=0]
+
+    evalsTo """
+      "civet coffeeRange"
+      [100...0]
+    """, [100>=..>0]
+
+    evalsTo """
+      "civet coffeeRange"
+      [' '..'~']
+    """, [' '..'~']
+
+    evalsTo """
+      "civet coffeeRange"
+      [' '...'~']
+    """, [' '...'~']
+
+    evalsTo """
+      "civet coffeeRange"
+      ['~'..' ']
+    """, ['~'>=..>=' ']
+
+    evalsTo """
+      "civet coffeeRange"
+      ['~'...' ']
+    """, ['~'>=..>' ']
+
   testCase """
     [0..10]
     ---
@@ -34,7 +75,25 @@ describe "coffeeRange", ->
     "civet coffeeRange"
     [0...256]
     ---
-    ((s, e) => {let step = e > s ? 1 : -1; return Array.from({length: Math.abs(e - s)}, (_, i) => s + i * step)})(0,256)
+    var revRange: (start: number, end: number) => number[] = (start, end) => {
+      const length = start - end;
+      if (length <= 0) return [];
+      const arr = Array(length);
+      for (let i = 0; i < length; ++i) {
+        arr[i] = start - i;
+      }
+      return arr;
+    };
+    var range: (start: number, end: number) => number[] = (start, end) => {
+      const length = end - start;
+      if (length <= 0) return [];
+      const arr = Array(length);
+      for (let i = 0; i < length; ++i) {
+        arr[i] = i + start;
+      }
+      return arr;
+    };
+    ((s, e) => s > e ? revRange(s, e) : range(s, e))(0,256)
   """
 
   testCase """
@@ -43,7 +102,25 @@ describe "coffeeRange", ->
     "civet coffeeRange"
     [0..255]
     ---
-    ((s, e) => {let step = e > s ? 1 : -1; return Array.from({length: Math.abs(e - s) + 1}, (_, i) => s + i * step)})(0,255)
+    var revRange: (start: number, end: number) => number[] = (start, end) => {
+      const length = start - end;
+      if (length <= 0) return [];
+      const arr = Array(length);
+      for (let i = 0; i < length; ++i) {
+        arr[i] = start - i;
+      }
+      return arr;
+    };
+    var range: (start: number, end: number) => number[] = (start, end) => {
+      const length = end - start;
+      if (length <= 0) return [];
+      const arr = Array(length);
+      for (let i = 0; i < length; ++i) {
+        arr[i] = i + start;
+      }
+      return arr;
+    };
+    ((s, e) => s > e ? revRange(s, e - 1) : range(s, e + 1))(0,255)
   """
 
   testCase """
@@ -69,7 +146,25 @@ describe "coffeeRange", ->
     "civet coffeeRange"
     [x - 5 .. x + 5]
     ---
-    ((s, e) => {let step = e > s ? 1 : -1; return Array.from({length: Math.abs(e - s) + 1}, (_, i) => s + i * step)})(x - 5 , x + 5)
+    var revRange: (start: number, end: number) => number[] = (start, end) => {
+      const length = start - end;
+      if (length <= 0) return [];
+      const arr = Array(length);
+      for (let i = 0; i < length; ++i) {
+        arr[i] = start - i;
+      }
+      return arr;
+    };
+    var range: (start: number, end: number) => number[] = (start, end) => {
+      const length = end - start;
+      if (length <= 0) return [];
+      const arr = Array(length);
+      for (let i = 0; i < length; ++i) {
+        arr[i] = i + start;
+      }
+      return arr;
+    };
+    ((s, e) => s > e ? revRange(s, e - 1) : range(s, e + 1))(x - 5 , x + 5)
   """
 
   testCase """
@@ -127,5 +222,14 @@ describe "coffeeRange", ->
     "civet coffeeRange"
     [a..<b]
     ---
-    ((s) => Array.from({length: b - s}, (_, i) => s + i))(a)
+    var range: (start: number, end: number) => number[] = (start, end) => {
+      const length = end - start;
+      if (length <= 0) return [];
+      const arr = Array(length);
+      for (let i = 0; i < length; ++i) {
+        arr[i] = i + start;
+      }
+      return arr;
+    };
+    range(a,b)
   """